The One Health approach investigates the complexities surrounding the interplay between the animal, human and environmental domains. Zoonotic pathogens, such as Escherichia coli (E. coli) O157, which have animal reservoirs, also have direct impact on public health. Cattle are the primary reservoir of E. coli O157, however infection with this bacterium is asymptomatic. Infected cattle appear healthy and have normal growth rates and milk production abilities. Each year, thousands of Canadians become ill following exposure to E. coli O157. To reduce this public health risk, immunization of cattle would be an effective intervention. Several models have shown that on-farm pathogen reduction programs would significantly reduce the risk of human illness.